Molten salt synthesis of alkaline earth titanates, zirconates and their solid solutions

Abstract

A particulate mixture of an alkali metal hydroxide solvent, a reactant selected from the group consisting of titanium oxide, zirconium oxide and mixtures thereof, and an alkaline earth reactant selected from the group consisting of barium oxide, strontium oxide, and mixtures thereof, is heated to melt the alkali metal hydroxide solvent in which the reactants dissolve and react precipitating a titanate, zirconate or solid solutions thereof.

What is claimed is: 
     
       1. A process for producing a product selected from the group consisting of an alkaline earth titanate, an alkaline earth zirconate, and an alkaline earth titanate zirconate wherein the alkaline earth component is selected from the group consisting of barium, strontium and mixtures thereof, which consists essentially of providing a particulate first reactant selected from the group consisting of TiO 2 , ZrO 2  and mixtures thereof in at least stoichiometric amount or particulate precursor therefor, providing a particulate second reactant which is an alkaline earth oxide selected from the group consisting of BaO, SrO, and mixtures thereof in at least stoichiometric amount or particulate precursor therefor, providing an alkali metal hydroxide selected from the group consisting of sodium hydroxide, potassium hydroxide and mixtures thereof, forming a mixture of said reactants or precursors therefor and said hydroxide solvent, said hydroxide solvent being used in an amount of at least about 20% by weight of the total amount of said reactants and said hydroxide solvent, heating said mixture to a reaction temperature at least sufficient to melt said hydroxide solvent and form said product, each said precursor decomposing completely at or below said reaction temperature to form said oxide and by-product gas, said hydroxide solvent in molten form being a solvent for said reactants, maintaining said reaction temperature dissolving and reacting said reactants in said molten solvent and precipitating said product, recovering said precipitated product by dissolving said hydroxide solvent and separating said precipitated product from the resulting solution. 
     
     
       2. The process according to claim 1 wherein said reactant is TiO 2  and said alkaline earth oxide is BaO. 
     
     
       3. The process according to claim 1 wherein said reactant is TiO 2  and said alkaline earth oxide is SrO. 
     
     
       4. The process according to claim 1 wherein said reactant is TiO 2  and said alkaline earth oxide is a mixture of BaO and SrO. 
     
     
       5. The process according to claim 1 wherein said reactant is ZrO 2  and said alkaline earth oxide is BaO. 
     
     
       6. The process according to claim 1 wherein said reactant is ZrO 2  and said alkaline earth oxide is SrO. 
     
     
       7. The process according to claim 1 wherein said reactant is a mixture of TiO 2  and ZrO 2  and said alkaline earth oxide is BaO. 
     
     
       8. The process according to claim 1 wherein said reactant is a mixture of TiO 2  and ZrO 2  and said alkaline earth oxide reactant is SrO. 
     
     
       9. The process according to claim 1 wherein said reactant is a mixture of TiO 2  and ZrO 2  and said alkaline earth oxide reactant is a mixture of BaO and SrO. 
     
     
       10. The process according to claim 1 wherein said hydroxide solvent is a mixture comprised of 50 mole % sodium hydroxide and 50 mole % potassium hydroxide.